1. Field of the Invention
The invention relates to a process for the production of dimedone from isophorone.
2. Prior Art
Dimedone has various uses as an intermediate product in the chemical industry, such as, in the production of pharmaceuticals (U.S. Pat. Nos. 3,775,435 and 3,823,164), herbicides or pesticides (German OS No. 22 01 668 and U.S. Pat. No. 3,976,785) and polymerizates (Japanese Pat. No. 77 47949), in photochemistry (U.S. Pat. No. 2,944,899 and Japanese Pat. No. 78 33143) and in analyticals (German OS No. 25 12 586).
Various methods for the production of dimedone are known in the literature. In Organic Synthesis, Coll. II, 200 (1943), a process is mentioned which starts out from malonic ester and mesitylic oxide. T. Henshall et al. J. Amer. Chem. Soc. 77, 6656 (1955), obtained dimedone by the cyclization of 3,3-dimethyl-5-oxo-hexanoic acid with sulphuric acid. G. B. Payne, J. Org. Chem. 24, 719 (1959), produces dimedone from isophorone with the help of a multistage, complicated process: ##STR1##
All these processes have various disadvantages, such as, low yields, poor accessability to the 3,3-dimethyl-5-oxo-hexanoic acid, and large amounts of organic waste, but particularly in the latter case, many individual reaction steps.